Mycoplasmas (class Mollicutes) are wall-less bacteria that are pathogenic in man, lower animals, plants and arthropods. Though not fatal, they have been associated with a number of diseases involved with immunocompromised hosts -- including AIDS. Genetic and physiological research studies for this organism have been hampered due to the inability to obtain stable genetic mutants, and the lack of a genetic transfer system. Stress response is the most highly conserved response in nature and has been found in all organisms tested -- from bacteria to plants to humans. Upon stressful stimuli, cells rapidly synthesize a de novo set of proteins. The heat shock family of proteins is the most abundant and most conserved set of proteins in nature. The stress response has significant implications in providing a first line of defense for infectious diseases, autoimmunity, and immunopathology. The overall objective of the proposed study is to provide initial studies for unraveling this response in M. genitalium. Because of this organism's limited coding capacity, it provides an excellent model for determining the least number of genes required for self existence and/or pathogenicity. Specific aims are: 1) to complete the DNA sequence of four heat shock genes previously identified, 2) to map these genes to the recently published physical map and 3) to expand the repertoire of known M. genitalium heat shock genes.